maths question 一題 <15marks>

很無棱兩可的問題...

可以有兩種答案:

若下午用去的十分之三元是未計上午用去 十分之三,那共用了:
= $250 x (3/10) + $250 x (3/10)
= $75 + $75
= $150

若下午用去的十分之三元是已經計上午用去 十分之三,那共用了:
= $250 x (3/10) + {$250 - [$250 x (3/10)]} x (3/10)
= $75 + ($250 -$75) x (3/10)
= $75 + $175 x (3/10)
= $75 + $52.5
= $127.5

250*(3/10+3/10)

=250*6/10

=150(元)

共用了150元.

共用了:
250x(3/10+3/10)=150(元)

250x(3/10+3/10)
=250x6/10
=150元